Analysis of variations in the saltating sand grain transport velocity

Resumo

A technique is developed for retrieving the vertical profile of the mass saltation flux from measurements of the saltating sand mass concentration and wind velocity in the surface air layer. The technique is based on the solution of direct and inverse problems of the saltation sand dynamics and aimed at determining the sliding coefficient of sand grains. The calculation results for the sliding coefficient of sand grains are compared with data of measurements in wind channels. The conditions under which saltating sand trajectories fall in the height ranges from 5 to 10 mm and from 10 to 20 mm are revealed. The effect of variations in the diameter, lift-off velocity and angle, and friction velocity on the sliding coefficient of sand grains is analyzed. The sliding coefficient for 100-μm diameter sand particles is estimated for the first time.